ANAHEIM, Calif. — Eleven elementary school students and their driver were injured when a school bus jumped a curb today and rammed into trees in Southern California, authorities said.

Three of the injured — the driver and two of the children — were taken to hospitals in critical condition after the crash, Anaheim police Lt. Bob Dunn said. The other nine students had minor injuries.

Television news reports show the Orange Unified School District bus tilted sideways and leaning against a tree on a roadside embankment next to Anaheim Hills Golf Course. Police say no other vehicles were involved in the crash.

The driver was trapped inside the bus, and firefighters removed him before he was taken to the hospital.

Witness Andrea Shurtz, one of many people driving nearby who saw the crash, said the bus was going very fast when it hit a curb and appeared to go airborne.

“It came flying down the hill,” Shurtz told KABC-TV, “and took out trees along the way.”

Shurtz said the driver and several students were hanging out of the bus’s windows and yelling for help from passing drivers.

“Kids were screaming. Gas was pouring out the back,” Shurtz said. “People just came running from everywhere.”

The bus was equipped with seat belts, police said, but it wasn’t clear how many of the students were wearing them at the time of the crash.

The California Highway Patrol will take over the investigation. There is no immediate word on the cause.

The crash was in Anaheim Hills, an affluent community within the city of Anaheim about 10 miles east of Disneyland and 30 miles southeast of downtown Los Angeles.